Generate Unique Indices for Lists of EmbeddedDocs

- Unique indices are now created in the database for EmbeddedDocument
  fields when the EmbeddedDocument is in a ListField
- Closes Issue #358
Update Tests for EmbeddedDocument Unique Indicies
Update to Changelog to include Fix for #358
Merge pull request #806 from mmelliso/mmelliso/indexing

Generate Unique Indices for Lists of EmbeddedDocs